It is frequently desired to include nonionic surfactant in granular laundry detergent compositions as it gives good oily soil detergency and can reduce foam levels, which is beneficial in detergent compositions for use in automatic washing machines.
Nonionic surfactant may be introduced into granular detergent compositions during the manufacture thereof along with other components such as anionic surfactants, builders etc. manufacturing requirements can place an upper limit to the amount of nonionic surfactant which can be included.
Detergent compositions with relatively high quantities of nonionic surfactant may be required as detergent compositions in their own right or for dosing to other detergent compositions to increase the proportion of nonionic surfactant in the combined composition.
The present application relates both to the inclusion of nonionic surfactant in fully formulated granular compositions and to nonionic-surfactant-containing granular compositions with high nonionic content for dosing to other detergent compositions.
Nonionic-surfactant-containing particles are disclosed for example in JP 08 027 498A (Kao), which discloses a silica based carrier having an oil absorption capacity of at least 80 ml/g and capable of providing a particle having up to 50% by weight of nonionic surfactant.
EP 521 635A (Unilever) discloses the use of zeolite P having a silicon to aluminium ratio not greater than 1.33 (otherwise called zeolite MAP) as a carrier for liquid, viscous-liquid, oily or waxy detergent ingredients such as nonionic surfactant. The zeolite MAP can be used in the form of a powder, granulate or as a component of a detergent composition.
Problems are now being experienced with the rate of dissolution of nonionic surfactant from granulates comprising nonionic surfactant absorbed in a carrier, referred to herein as dispersion. In particular, problems have been encountered such as poor dispersion of the powder into the wash water in the dispenser drawer of an automatic washing machine. A gritty, viscous mass may remain in the dispenser drawer. Further, powder compositions entrained in the wash water may not break-up and disperse adequately. Undispersed particles of powder compositions may remain in the wash water. These can adhere to clothes and cause local damage. Undissolved powder composition can remain on the clothes after washing. There are particular dispersion problems where nonionic surfactant is absorbed onto carrier particles comprising a high proportion of aluminosilicate.
Addition of oils to powdered detergents as hydrophobing agents, thus aiding dispensing is disclosed in EP 0648 259 (Henkel).
U.S. Pat. No. 5,514,295 (Amway/Flower) discloses granular detergent compositions comprising a detergent (base) powder to which a liquefied intimate mixture of a nonionic surfactant, a fatty acid and a fatty alcohol is applied.
EP 694 608A (Procter & Gamble) discloses a premix of a specific nonionic surfactant (polyhydroxy fatty acid amide, glucamide) with a glyceride as a structurant. The premixes may also contain ethoxylated nonionic surfactant.
CA 2308932 (Henkel) discloses a process for the production of surfactant granules in which nonionic surfactant and polyalkylene glycol are premixed.
GB 1,578,288 (Colgate-Palmolive) discloses a detergent composition mainly for formation into solid pellets comprising a water-soluble soap component, a water soluble synthetic detergent component (anionic or nonionic surfactant) and a solvent component (which is a mixture of water soluble and non-water soluble solvents). Addition of further components including builders (zeolites and phosphates) is described.
The present inventors have now found that the rate of dissolution of nonionic-surfactant-containing granular compositions can be improved if the nonionic surfactant is intimately blended with a water-insoluble liquid, before preparing the granular composition.